Extraction optimisation,purification and major antioxidant component of red pigments extracted from Camellia japonica

The optimised extraction conditions of red pigments (RP) from Camellia japonica obtained with an orthogonal design L₉(3⁴) were solid/liquid ratio, temperature, pH and extraction time as 1/10, 60 °C, 1.5 and 4 h, respectively. The RP were then purified by the macroporous resin method, which showed the resin LX-68 was appropriate for purifying the pigments from C. japonica. The antioxidant activities of these pigments were also investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical in vitro model systems. The DPPH scavenging activity of pigment extract was comparable to that of standard butylated hydroxyanisole (BHA). The IC₅₀ values of the RP and BHA were 4.55 and 4.17 μg ml⁻¹, respectively. The pigments showed higher hydroxyl radical-scavenging activities than that of mannitol at the same concentration. Following activity-oriented separation, (−)-epicatechin was isolated as an active principle, which exhibited excellent DPPH free radical scavenging activities with IC₅₀ 5.08 μg ml⁻¹.     

Profiling of in vitro neurobiological effects and phenolic acids of selected endemic Salvia species

The ethyl acetate and methanol extracts from 16 Salvia L. species were screened for their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, and tyrosinase; the enzymes linked to neurodegeneration. Their antioxidant activity was also tested using DPPH radical scavenging, metal-chelation, and ferric-reducing antioxidant power (FRAP) assays. Total flavonoid content of the extracts was determined by AlCl₃ reagent, while HPLC technique was applied for analysis of various phenolic acids in the extracts. The extracts exerted weak cholinesterase and tyrosinase inhibition, and remarkable inhibition against lipoxygenase (13.07 ± 2.73-74.21 ± 5.61%) at 100 μg ml⁻¹. The methanol extracts showed higher antioxidant activity in DPPH radical scavenging and FRAP assays. The extracts were analyzed for their gallic, protocateuchic, p-hydroxy-benzoic, vanillic, caffeic, chlorogenic, syringic, o- and p-coumaric, ferulic, rosmarinic, and tr-cinnamic acid contents and the methanol extract of Salvia ekimiana (153.50 mg 100 g⁻¹) was revealed to be the richest in terms of rosmarinic acid.     

Antioxidant activity of microwave-assisted extract of Buddleia officinalis and its major active component

Buddleia officinalis Maxim, commonly used as rice dye for festivals, was extracted with ethanol using microwave-assisted extraction and Soxhlet extraction. The antioxidant activities of microwave-assisted extract of B. officialis (MEB) and Soxhlet extract of B. officianils (SEB) at the optimum extraction conditions were evaluated and compared with synthetic antioxidant butylated hydroxytoluene (BHT) employing DPPH free radical assay, ABTS assay, total antioxidant activity and reducing power. MEB and SEB had stronger antioxidant activities than BHT in all assays except reducing power, and the effects decreased as follows: MEB > SEB > BHT. The total phenolic contents of MEB and SEB reached 113.56 mg/g and 100.94 mg/g dry weight of extract, respectively, expressed as pyrocatechol equivalents, while the total flavonoids contents were 75.33 mg/g and 62.56 mg/g dry weight of extract, respectively, expressed as catechin equivalents (P < 0.05). Higher phenolic and flavonoids compounds may be major contributors to their higher antioxidant activities. Following activity-oriented separation, luteolin was isolated as an active principle, which exhibited excellent free radical scavenging activities with DPPH IC₅₀ 3.09 μg/ml and ABTS IC₅₀ 2.20 μg/ml.     

Antioxidant and radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.     

Antioxidant and antiacetylcholinesterase activities of five plants used as Portuguese food spices

In the present work, we report the results of a study aimed at evaluating the antiradical activity, the antioxidant activity and the acetylcholinesterase (E.C. 3.1.1.7.) inhibitory capacity of essential oils, ethanol and boiling water extracts from five aromatic herbs growing wild in Portugal and used in traditional food preparations: fennel (Foeniculum vulgare), mint (Mentha spicata), pennyroyal (Mentha pulegium), rosemary (Rosmarinus officinalis) and wild thyme (Thymus serpyllum). The water extracts of M. spicata and M. pulegium showed the highest radical-scavenging activity (DPPH test) values (IC₅₀ = 5.7 ± 0.4 and 8.9 ± 0.2 μg ml⁻¹ respectively). This activity was higher than that found with the standard antioxidant BHT. The ethanol extracts of M. spicata, T. serpyllum and F. vulgare showed the highest antioxidant activities measured by the β-carotene/linoleic acid assay, IC₅₀ = 36.9 ± 0.1, 41.2 ± 0.1 and 68.7 ± 0.1 μg ml⁻¹, respectively. The inhibition of AChE was higher in the essential oil fraction. The highest activity was found for R. officinalis with an IC₅₀ = 69.8 ± 0.1 μg ml⁻¹.     

Antioxidant potential of solvent extracts of Kappaphycus alvarezii (Doty) Doty – An edible seaweed

Various solvent extracts of Kappaphycus alvarezii, an edible red seaweed (family Solieriaceae) were screened for total phenol content and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferrous ion chelating activity, reducing power and antioxidant activity assays in a linoleic acid system with ferrothiocyanate reagent (FTC). The total phenol content of different extracts of K. alvarezii varied from 0.683 ± 0.040% to 2.05 ± 0.038%. The radical-scavenging activity of ethanol extract was, as IC₅₀ 3.03 mg ml⁻¹, whereas that of the water extract was IC₅₀ 4.76 mg ml⁻¹. Good chelating activity was recorded for methanol extract (IC₅₀ 3.08 mg ml⁻¹) wherein 67.0 ± 0.924% chelation was obtained using 5.0 mg ml⁻¹ of extract. The reducing power of the samples was in the following order: BHT > methanol > ethanol > ethyl acetate > water > hexane. But, in the linoleic acid system, the ethanol extract proved superior to the synthetic antioxidants butylated hydroxytoluene (BHT). Hence, these extracts could be considered as natural antioxidants and may be useful for curing diseases arising from oxidative deterioration.     

Antioxidant potentials and rosmarinic acid levels of the methanolic extracts of Salvia verticillata (L.) subsp. verticillata and S. verticillata (L.) subsp. amasiaca (Freyn & Bornm.) Bornm

This study was designed to examine the in vitro antioxidant activities and rosmarinic acid levels of the methanol extracts of Salvia verticillata subsp. verticillata and S. verticillata subsp. amasiaca. The extracts were screened for their possible antioxidant activity by two complementary test systems, namely DPPH free radical-scavenging and β-carotene/linoleic acid systems. In the first case, S. verticillata subsp. verticillata was superior to the subsp. amasiaca with an IC₅₀ value of 14.5 ± 1.21 μg mg⁻¹. In the β-carotene/linoleic acid test system, inhibition capacity of S. verticillata subsp. verticillata was 74.4 ± 1.29%. Antioxidant activities of BHT, ascorbic acid, curcumin and α-tocopherol were determined in parallel experiments. Activity of rosmarinic acid was also screened for better establishing the relationship between rosmarinic acid level and antioxidant activity for the plant extracts. S. verticillata subsp. verticillata had the highest rosmarinic acid level with a value of 28.7 ± 0.89 μg mg⁻¹. There is a strong correlation between the rosmarinic acid level and antioxidant activity potential. Our results showed that rosmarinic acid and its derivatives are more likely to be responsible for most of the observed antioxidant activities of Salvia species.     

Polyphenol contents and in vitro antioxidant activities of lyophilised aqueous extract of kiwifruit (Actinidia deliciosa)

The aim of this study was to determine the antioxidant potency and total phenolic and flavonoid contents of kiwifruit (Actinidia deliciosa) in vitro by analysing the radical scavenging activity of lyophilised water extract from kiwifruit (LEK) for 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picryl-hydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), and superoxide anion radical (O₂⁻) as well as the total reducing power by FRAP and CUPRAC assays and the metal chelating activities. LEK showed efficient radical scavenging activity with DPPH, ABTS, DMPD, and O₂⁻ radicals; ferric (Fe³⁺) and cupric (Cu²⁺) ion reducing power and metal chelating activities. Moreover, the amounts of phenolic compounds, such as caffeic acid, ferulic acid, syringic acid, ellagic acid, catechol, pyrogallol, p-hydroxy benzoic acid, vanillin, p-coumaric acid, gallic acid, quercetin, ??-tocopherol and ascorbic acid, in LEK were quantified by LC-MS-MS. The results show that pyrogallol (2070.0 mg/kg LEK) is the main phenolic compound responsible for the antioxidant and radical scavenging activities of LEK. Finally, total phenolic and flavonoid contents were determined as gallic acid (GAE) and quercetin equivalents (QE). The GAE and QE values in LEK were 16.67 ± 2.83 ??g GAE/mg and 12.95 ± 0.52 ??g QE/mg, respectively. The results suggest that consumption of kiwifruit (A. deliciosa) can be beneficial effects due to its antioxidant properties.     

Antioxidant activity of ethanolic extract of Cortex fraxini and use in peanut oil

Cortex fraxini was extracted with 95% ethanol to obtain a crude antioxidant extract. The antioxidant activity was evaluated using the linoleic acid peroxidation method and the free radical scavenging assays, namely 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. Cortex fraxini extract (CFE) showed high inhibition of peroxidation of linoleic acid when compared with butylated hydroxytoluene (BHT). CFE also exhibited excellent scavenging activity on DPPH and hydroxyl radicals. Total antioxidant activity was measured by the reduction of Mo(VI) to Mo(V) by the extract, and subsequent formation of a green phosphate/Mo(V) complex at acid pH. CFE had significant total antioxidant activity and the effects were increased with increasing reaction time. The total phenolic content of the sample, analyzed by using Folin–Ciocalteu’s reagent, was 91.33 mg/g dry weight expressed as pyrocatechol equivalents. Then the suitability of CFE as an antioxidant was determined in peanut oil, and the decrease of lipid oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. CFE treatment significantly (P < 0.05) reduced lipid oxidation in peanut oil compared to the control. No significant differences (P = 0.05) in lipid oxidation were detected between CFE antioxidant and BHT antioxidant samples.     

Antioxidant properties of hot water extracts from Agrocybe cylindracea

Agrocybe cylindracea (DC: Fr.) Mre. was available in the form of fruit bodies, mycelia and fermentation filtrate. From these three forms, hot-water extracts were prepared and their antioxidant properties were studied. Antioxidant activities of hot-water extracts from fruit bodies, mycelia and filtrate were 63.6%, 81.6% and 56.8% at 20 mg ml⁻¹, respectively. EC₅₀ values in reducing power were 2.72, 3.97 and 3.09 mg ml⁻¹ whereas those in scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl radicals were 0.62, 1.66 and 0.82 mg ml⁻¹ for fruit bodies, mycelia and filtrate, respectively. At 20 mg ml⁻¹, the scavenging abilities of hydroxyl radicals were 80.1%, 57.0% and 54.3% for fruit bodies, mycelia and filtrate, respectively. With regard to EC₅₀ values in chelating abilities on ferrous ions, the hot-water extract from filtrate was better than that from mycelia. Total phenols were the major naturally occurring antioxidant components found in hot-water extracts and in the range of 23.74–30.16 mg g⁻¹. From EC₅₀ values obtained, it can be concluded that hot-water extracts from three forms of A. cylindracea were good in antioxidant properties.     

Systematic evaluation of natural phenolic antioxidants from 133 Indian medicinal plants

Total antioxidant capacities of 133 Indian medicinal plant species sampled from 64 families were assessed by ABTS, DPPH and FRAP assays, and their total phenolic contents measured by Folin–Ciocalteu assay. These species exhibited a broad range of antioxidant activities, varying from 0.16 to 500.70 mmol TEAC/100 g DW in the ABTS assay. The antioxidant activity values similarly varied with the DPPH and FRAP assays. Significant and positive linear correlations were found between total antioxidant capacities and phenolic contents (R = 0.89–0.97), indicating that phenolics were the dominant antioxidant constituents in the tested medicinal plants. Preliminary identification of the major phenolic compounds from 83 selected medicinal plants by reversed-phase HPLC revealed phenolic acids, tannins, flavonoids, curcuminoids, coumarins, lignans, and quinines. The fruit of Terminalia chebula, pericarp of Punica granatum and gall of Rhus succedanea showed very high levels of hydrolysable tannins, and the gum of Acacia catechu presented very high levels of catechin and epicatechin in addition to tannins. Major phenolics in many of the medicinal plants were identified for the first time (e.g., Euphorbia lathyrus, Ipomoea turpethum, and Picrorrhiza kurroa). This systematic investigation of a large number of Indian medicinal plants proved important for understanding their chemical constituents and functionality in Ayurvedic medicine, and contributes to the search for natural sources of potent antioxidants.     

Chemical composition,antioxidant and antibacterial activities of the essential oils isolated from Tunisian Thymus capitatus Hoff. et Link.

The chemical composition, antioxidant and antibacterial activities of essential oils isolated by hydrodistillation from the aerial parts of Tunisian Thymus capitatus Hoff. et Link. during the different phases of the plant development, and from different locations, were evaluated. The chemical composition was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The main components of the essential oils were carvacrol (62–83%), p-cymene (5–17%), γ-terpinene (2–14%) and β-caryophyllene (1–4%). The antioxidant activity of the oils (100–1000 mg l⁻¹) was assessed by measurement of metal chelating activity, the reductive potential, the free radical scavenging (DPPH) and by the TBARS assay. The antioxidant activity was compared with that of synthetic antioxidants: butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Both the essential oils and BHA and BHT showed no metal chelating activity. Although with the other methodologies, there was a general increase in the antioxidant activity, with increasing oil concentration, maxima being obtained in the range of 500 and 1000 mg l⁻¹ for flowering and post-flowering phase oils. Major differences were obtained according to the methodology of antioxidant capacity evaluation. Antibacterial ability of Th. capitatus essential oils was tested by disc agar diffusion against Bacillus cereus, Salmonella sp., Listeria innocua, four different strains of Staphylococus aureus (C15, ATCC25923, CFSA-2) and a multi-resistant form of S. aureus (MRSA-2). Antibacterial properties were compared to synthetic antibiotics. Higher antibacterial activity was observed with the flowering and the post-flowering phase essential oils.     

Antioxidant potential of ethanolic extract of Polygonum cuspidatum and application in peanut oil

Polygonum cuspidatum was extracted with 95% ethanol to obtain a crude antioxidant extract. P. cuspidatum extract (PCE) had a very high content of total phenol, which was 104.83 ± 8.58 mg/g dry weight, expressed as pyrocatechol equivalent. PCE exhibited excellent antioxidant activity, as measured using α,α-diphenyl-β-picryhydrazyl (DPPH) and total antioxidant assays. It also showed a high lipid antioxidant activity and hydroxyl radicals scavenging activity. A positive correlation was found between the reducing power and the antioxidant activity of PCE, which was found to be comparable to resveratrol and butylated hydroxytoluene (BHT). Then the suitability of PCE as an antioxidant was determined in peanut oil, and the decrease of oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. PCE treatment significantly (P <  0.05) reduced lipid oxidation in peanut oil compared to resveratrol and BHT.     

Preliminary evaluation of nutraceutical and therapeutic potential of raw Spondias pinnata K., an exotic fruit of India

The underutilized, edible green raw (whole) fruits of amra, Spondias pinnata K. (Anacardiaceae family) from the eastern region of India were investigated for their nutraceutical and therapeutic potential. A thorough nutritional characterization of this fruit demonstrated it as a source of energy (348 kcal/100 g DM), phenolic compounds, natural antioxidants and minerals. It is also a moderate source of ascorbic acid, malic acid, calcium, phosphorus and other nutrients. The phytochemical screening revealed 5.12 ± 0.32 mg 100 g^− 1 DM of alkaloids followed by saponins and tannins. All assays were carried out in three different solvent extracts of the fruit. Total phenolic, flavonoid and flavonol contents were obtained as 210 ± 1.89 mg GAE, 28.0 ± 0.91 mg CE and 9.97 ± 0.72 mg RE respectively in 100 mg mix solvent extract (MSE). Antioxidant activity of different extracts (as DPPH scavenging) ranged from 0.73 to 0.59 mg ml^− 1 as IC₅₀ value, ABTS with a trolox equivalent antioxidant concentration (TEAC) value as 0.68 to 0.83 and FRAP 5.97 to 7.93 mg TE 100 mg^− 1 extract. LC- MS/MS analysis revealed the presence of gallic acid, salicylic acid, chlorogenic acid, ellagic acid, p-coumaric acid, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, quercetin, catechin, myrecetin and rutin. The MSE showed the highest antimicrobial activity (against Listeria monocytogenes (MIC 1.8 mg ml^− 1)) and ??-amylase inhibition capacity (as IC₅₀: 29.3 mg ml^− 1 extract). GC/MS screening showed the presence of vitamin E, furfural, phytosterol, campesterol and fatty acids. Analysis of volatile flavor showed isopropyl myristinate as a major compound followed by the other monoterpenes and sesquiterpenes. The current study explains the nutritional as well as medicinal utility of the fruit which is a rich source of minerals and antioxidants such as phenols and flavonoids.     

Determination of isoflavone content and antioxidant activity in Psoralea corylifolia L. callus cultures

Relation between isoflavones production and antioxidant activity in Psoralea corylifolia cell cultures was studied. High performance liquid chromatography analysis revealed that root-derived callus cultures produced maximum amount of daidzein whereas genistein by leaf-derived callus. Cell cultures grown under continuous illumination (40-μmol m⁻² s⁻¹) produced several-fold more isoflavones daidzein (2.28% dry wt) and genistein (0.21% dry wt) than that of field grown plants. The antioxidant activity of extracts was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, phosphomolybdenum assay and correlated with the content of total phenolics in the extracts. Calli grown under continuous illumination exhibited strong antioxidant activities compared to dark grown callus cultures and explants materials.     

Antioxidant properties of dried product of ‘haba-nori’, an edible brown alga, Petalonia binghamiae (J. Agaradh) Vinogradova

Dried ‘haba-nori’ Petalonia binghamiae, a brown alga, is a traditional food in the fisheries towns in Japan. To determine the antioxidant properties of the dried P. binghamiae, assays for antioxidant activities, including ferrous-reducing power, ferrous ion chelating, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and scavenging of a superoxide anion radical-generated by non-enzymatic system were tested in this study. A water extract solution contained total phenols at about 75 μmol phloroglucinol equivalents/g dry sample and showed strong antioxidant activities in the reducing power, DPPH radical and superoxide anion radical scavenging assays. The antioxidant activities were detected in high-molecular (>100 kDa), 10–30 kDa, and low-molecular (<5 kDa) fractions and were correlated with, not only phenolic compounds, but also brown compounds. The radical- scavenging activities were increased by heat treatment at 121 °C for 1 h. These results suggest that P. binghamiae is both a useful seafood and a healthy food with antioxidant activity.     

Effects of genotype and treatment on the antioxidant activity of sweet potato in Taiwan

Six genotypes of sweet potato commercially available in Taiwan, including TNG57, TNG66, TNG68, TYY1, RP and WP, were used as samples in this study of the effects of steaming and kneading with pre-steaming treatments on the antioxidant components and antioxidant properties of methanolic extracts. Steam treatment increased the total phenols contents of all genotypes (2–13 times), flavonoids content of RP (1.3 times) and anthocyanins contents of RP and WP (5–6 times). Steam treatment also increased the reducing power and scavenging DPPH radical effect of sweet potato flours. For the methanolic extracts of steamed and kneaded flours, reducing powers were 0.02–1.70 at 5.0 mg ml⁻¹ and the scavenging effects on DPPH radicals were 19–92% at 2.5 mg ml⁻¹. Both showed the order of RP > WP > TYY1 and TNG66 > TNG57 and TNG68. However, the chelating effect of the six genotypes at 1.0 mg ml⁻¹ ranged from 50% to 73%. Contents of total phenols, flavonoids, and anthocyanins of sweet potato flours were significantly positively correlated with the reducing power and scavenging DPPH radical effects. After steaming and kneading treatments, RP showed the highest increase in the contents of total phenols, flavonoids and anthocyanins among the six genotypes studied.     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

Residue levels of food-grade antioxidants in postharvest treated in-pod peanuts during five months of storage

In order to investigate residue levels of butylated hydroxyanisole (BHA), propyl paraben (PP) and butylated hydroxytoluene (BHT) during storage, eight-hundred kilograms of bulk peanuts were treated with the following antioxidant emulsions: BHA (1802 μg g⁻¹), BHA–PP (1802 μg g⁻¹ + 1802 μg g⁻¹) M1 and BHA–PP–BHT mixtures (1802 μg g⁻¹ + 901 μg g⁻¹ + 2204 μg g⁻¹) M2 and (1802 μg g⁻¹ + 1802 μg g⁻¹ + 2204 μg g⁻¹) M3. Residues were determined in peanut pod and seed tissues at 1-month intervals during the storage. While the reduction levels of BHA and PP in pods at the end of the storage period ranged from 66% to 76%, BHT levels were decreased extensively (86%). Twenty-four hours after peanuts were treated, antioxidant emulsions effectively seeped into the seeds and low levels of these chemicals were detected during the assay. Residues of PP in seeds were lower (62%) than the other antioxidants. Although the doses used were higher than those approved for food-grade antioxidants in stored peanuts, the residue levels in seeds (32.8–0.02 μg g⁻¹) did not exceed the maximum residue limits during the storage period.     

Evaluation of antioxidant activities and total phenolic contents of typical malting barley varieties

Fourteen typical malting barley varieties from China were evaluated for their DPPH radical, ABTS radical cation and superoxide anion radical scavenging activities, reducing power, metal chelating activities, and total phenolic contents (TPC). All barley samples exhibited significant antioxidant activities determined by different assays, and contained significant levels of phenolic compounds. Gan4 and Wupi1 barley exhibited the highest DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power. Gan4 and Humai16 barley showed the highest TPC, whereas the highest superoxide anion radical scavenging activity and metal chelating activity were found in Huaimai19 and Ken3 barley, respectively. The Pearson correlation analysis revealed that the TPC showed strong correlations with DPPH radical scavenging activity, ABTS radical cation scavenging activity, and reducing power (P < 0.01), whereas its correlations with superoxide anion radical scavenging activity and metal chelating activity were poor (P > 0.05). Moreover, DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power were well positively correlated with each other (P < 0.01). Principal component analysis (PCA) was applied to understand the interrelationships among the measured antioxidant activity evaluation indices, and to gain an overview of the similarities and differences among the 14 barley varieties.